1. Technical field of the Invention
The present invention relates to a preloaded recoilless gun of a disposable type as an AT4, AT4 CS, AT4 CS AST and other equally valuable support weapons, which are normally ready for missions requiring an immediate action of effective fire. More particularly, the invention relates to a weapon having a barrel or launch tube and a projectile or shell preloaded therein together with a propellant charge, which is pro-vided with means for providing, so called, IM (Insensitive Munitions) characteristics during all kinds of operations, be it handling, transport and storing or standing by for immediate firing of support weapons of the indicated type.
2. Description of Related Art
When handling, transporting and storing, or being in a state of alert with, weapons of the initially mentioned kind, e.g. individually, during troop movements, trans-porting and storing in boxes, during attacking or defending progress or otherwise, there is in some cases a potential chance of an accidental firing of the propellant charge and a closely following detonation, if the shell should exit the barrel of the weapon, which would lead to possible fatal consequences.
Certain standard tests have been set for testing weapons, ammunition and missiles to determine if these fulfil safety criteria in this respect. Examples of such tests are “Bullet impact test”, “Fragment impact test”, “Fast Cook-off test” and “Slow Cook-off test”. If those tests show that a weapon system tested acts within acceptable limits, such a system is classified as an Insensitive Munition (IM) weapon system.
In this connection, reference might be made to US-A1-2005/0193917, which shows an example of a passive venting apparatus and method for a rocket motor or ordnance device containing propellant or explosive material enclosed in a case, which presents an explosion hazard when subjected to external heat. An alternative example configured with an IM-lock for weapons having preloaded projectiles is disclosed in EP-A1-1808664. In this example, when a certain temperature is reached, the inner area of the barrel is deformed by means of an element of SMA (Shape Memory Alloy).
It is desirable to provide enhanced IM-characteristics to such extent that the “Fast Cook-off” test is passed, that is the active venting means will start a venting in a shorter time after heating is commenced than with a passive venting system. One irrevocable demand is that the overpressure in the charge chamber is vented before the propellant charge detonates. Further, in certain cases it is desirable that all fragments and debris are kept within a radius of 15 m from the fire site.
However, up till now the related technical field of preloaded recoilless guns of the initially mentioned disposable type lacks a suitable solution regarding providing an improved wenting means adapted for use in providing enhanced IM-characteristics.